Isotopic uranium activity ratios in California groundwater

Wong, Carolyn; Okamoto, Howard S.; Milea, Alexis; Perera, S. Kusum; Baumann, Frank J.

doi:10.1002/j.1551-8833.1999.tb08623.x

Cited by 11 publications

(6 citation statements)

References 3 publications

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“…The specific activity of uranium in drinking water generally is higher than that of natural uranium due to an elevated concentration of uranium-234 in drinking water relative to natural uranium (Karpas et al 2005). Typical values for the specific activity of uranium in drinking water in the range 0.8-1.3 pCi µg -1 have been estimated from isotopic compositions of uranium found in public water systems (Federal Register 56, July 18, 1991;Wong et al 1999;EPA 2007b). In the present report, a rounded central estimate of 1 pCi µg -1 is used as the specific activity of uranium in drinking water and for consistency is also applied to air.…”

Section: Resultsmentioning

confidence: 99%

Fisk-based criteria to support validation of detection methods for drinking water and air.

MacDonell¹,

Bhattacharyya²,

Finster³

et al. 2009

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Section: Resultsmentioning

confidence: 99%

Fisk-based criteria to support validation of detection methods for drinking water and air.

MacDonell¹,

Bhattacharyya²,

Finster³

et al. 2009

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“…Vapor-liquid fractionation factors for C, Cl and H in TCE were discussed for its utility in investigating sites with soil vapor extraction or soil bioventing operations. Wong et al (1999) measured the relative abundance of the uranium isotopes U-234 and U-238 in groundwaters in California using three mass measurement techniques and two radiochemical techniques. Based on the activity and mass ratios, they calculated a mass-to-conversion factor of 0.79 pCi/μL, which was recommended to be the basis for estimating total U in water sources in California.…”

Section: New Sample Preparation Techniques and Data Analysismentioning

confidence: 99%

Chemical Species

Poppele¹,

Packer²,

Zhang³

et al. 2001

Water Environment Research

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This is a review of the 1999 literature that summarizes analytical techniques for the detection and quantification of organic and inorganic chemical species in drinking water, wastewater, and natural waters. The review emphasizes techniques that are relevant to the environmental engineering and science community. The review is divided into four main sections including new chemical methods, new biological methods, new sample preparation techniques, and new applications.

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“…Throughout several decades, a number of studies have reported large variations in groundwater ( 234 U/ 238 U) across different geological settings with essentially ubiquitous ( 234 U/ 238 U) > 1.0 (Cowart, 1981; Cuttell et al, 1988; Gilkeson et al, 1984; Herczeg et al, 1988; Hussain & Krishnaswami, 1980; Osmond et al, 1983; Paces et al, 2002). Given the potential impacts of variable ( 234 U/ 238 U) on drinking water regulations, Wong et al (1999) surveyed the isotopic variation in California groundwaters prior to the revised radionuclide rule to explore whether an appropriate conversion factor from mass to activity could be determined in a specific region. They found ( 234 U/ 238 U) from 0.78 to 2.27 and suggested a conversion factor of 0.79 pCi/μg based on an average ( 234 U/ 238 U) ratio of 1.32.…”

Section: Introductionmentioning

confidence: 99%

The importance of uranium isotope composition for gross alpha activity regulation

Scott¹,

Plechacek

Krinke³

2023

AWWA Water Science

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Uranium is a regulated contaminant (maximum contaminant level [MCL] 30 μg/L) that contributes to the gross alpha activity of groundwater. The adjusted gross alpha activity (MCL 15 pCi/L) is determined by subtracting the total uranium activity from the measured gross alpha activity. U.S. water utilities can use mass-based and radiochemical analysis methods for compliance monitoring of uranium. Mass-based measurements use a conversion factor of 0.67 pCi/μg of uranium to calculate the adjusted gross alpha activity. This conversion factor assumes that the activity of 234 U equals 238 U. Here, we present two decades of uranium isotope data measured by alpha spectrometry that shows 234 U activity typically exceeds 238 U. Using mass-based measurements, the total uranium activity is biased low causing artificial exceedances of the adjusted gross alpha activity. Therefore, water utilities with gross alpha activities >15 pCi/L should utilize radiochemical analyses for uranium for the most accurate calculation of adjusted gross alpha activity.alpha spectrometry, gross alpha activity, groundwater, uranium isotope ratios | INTRODUCTIONUranium is regulated by the United States Environmental Protection Agency (EPA) due to its toxicological properties (Dinocourt et al., 2015;Selden et al., 2009;Zamora et al., 1998). The radionuclides rule was updated in 2000 to include a uranium maximum contaminant level (MCL) of 30 μg/L (US EPA, 2015). The radionuclides rule also addresses gross alpha activity. When the gross alpha activity is measured above 15 pCi/L, analysis of uranium is required to determine the adjusted gross alpha activity (gross alpha minus the uranium and radon activities). Establishing compliance with the MCL requires four consecutive quarterly samples, and initial compliance is based on the running average of these four initial samples. Any exceedance of the MCL during this period or in subsequent sampling efforts triggers additional quarterly monitoring. Ultimately, any entry point in a drinking water distribution system must demonstrate four consecutive quarterly samples below the MCL to comply with the radionuclides rule for adjusted gross alpha activity. Because total uranium activity is subtracted from the gross alpha activity for compliance monitoring, quantification of the total uranium activity is a critical factor for adhering to this regulation.Both radiochemical and mass-based measurements are approved for compliance monitoring of uranium under federal rule when this analysis is triggered by a

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Isotopic uranium activity ratios in California groundwater

Cited by 11 publications

References 3 publications

Fisk-based criteria to support validation of detection methods for drinking water and air.

Fisk-based criteria to support validation of detection methods for drinking water and air.

Chemical Species

The importance of uranium isotope composition for gross alpha activity regulation

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